[time-nuts] Active antennas for a Thunderbolt...

[Didier Juges]

The coax is actually 50 feet of good quality 75 ohm cable that I bought for this (rated for satellite TV).  I have not measured the loss accurately but I did check it at 2GHz when I bought it and it was good. 

Didier



Tom Knox <actast at hotmail.com> wrote:

>
>Hi;
>Is your coax 50 or 75 ohm? Is it microwave rated? and have you tried
>changing coax length? None of these should be a major factor but could
>make a difference.
>Best Wishes;
>Thomas Knox
>
>
>
>> From: shalimr9 at gmail.com
>> Date: Mon, 30 Jul 2012 13:46:40 -0500
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] Active antennas for a Thunderbolt...
>> 
>> Chuck, 
>> 
>> I have one of the original red box TB.  It came with the Trimble
>Bullet antenna that is specified in the TB datasheet. 
>> 
>> The antenna works but gives extremely poor results.  The TB works
>much better with the Symmetricom antenna that is sometimes available on
>eBay. 
>> 
>> The Bullet antenna is usable with other GPS receivers,  so I know it
>is not bad.  Its just a poor match for the TB. 
>> 
>> Didier KO4BB
>> 
>> 
>> Chuck Harris <cfharris at erols.com> wrote:
>> 
>> >Ok, I'm getting a little puzzled.  I have a TB that came from one of
>> >the early groups sold by John Ackermann and TVB as part of the TAPR
>> >buy.
>> >It works nicely, but like all TB's, it is deaf as a post, and needs
>a
>> >high gain antenna.... When I first got the TB, I tried it with a
>> >Motorola
>> >hockey puck antenna, with about 17db gain, and if it is outside in
>the
>> >clear, it works nicely... but LH shows the satellites signals are
>all
>> >down in the mud.
>> >
>> >...So...
>> >
>> >I bought the active antenna that the TB data sheet said belonged
>with
>> >the TB, a 24045-10 bullet antenna, and *NO* satellites are visible..
>> >the antenna is dead.
>> >
>> >I'm no stranger to getting cheated on things I buy, so I chalked it
>up
>> >to bad luck, and put my Motorola hockey puck antenna back on my TB.
>> >
>> >...Then....
>> >
>> >A couple of days ago another active antenna became available, a
>> >Micro Pulse 1934NW/C 50db antenna from a DATUM INC GPSDO.  I checked
>> >its data sheet, and it powers off of +5V @ 38ma, so I bought it,
>> >hooked it up to my TB, and again *NO* satellites are visible... the
>> >antenna is dead.
>> >
>> >I put a "T" in the line, and the voltage heading up to the antenna
>is
>> >around +4.5V... The spec sheet says it will work down to +3V.
>> >
>> >Am I doing something wrong here?  Or am I just unlucky?
>> >
>> >-Chuck Harris
>> >
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>> 
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Sent from my Motorola Droid Razr phone with K-9 Mail. Please excuse my brevity.